Generally, an induction heater has such features as being excellent in energy-saving properties, being capable of heating a material rapidly, showing satisfactory temperature controllability and responsiveness, and providing a good working environment, as compared to other heaters.
If the induction heater is used in a rolling line (for instance, a hot rolling line), a skid mark on a rough bar can be reduced, and the precision of a plate thickness and a plate width over the whole length of the material can be increased. In addition, if low-temperature take-out from a heating furnace and compensation for thermal run down are also employed, high-speed rolling from the head to the tail end of the material is enabled. When a temperature of the tail end of the material is raised by the induction heater, it becomes possible even for a material which has not been rolled so far (for instance, a thin and long material), to be rolled. The induction heater has such various advantages, and accordingly various methods of using the induction heater are proposed for each facility, and are actually applied to each facility.
For instance, PTL 1 describes a method of controlling a surface temperature of a material at the time immediately after the material has passed through the induction heater to a certain target temperature or higher, and controlling an internal temperature of the material at the time to a certain target temperature or lower, by heating the material by the induction heater.